The invention had the object of finding novel compounds having valuable properties, in particular those which can be used for the preparation of medicaments.
The present invention relates to compounds and to the use of compounds in which the inhibition, regulation and/or modulation of kinase signal transduction, in particular by serine/threonine kinases, plays a role, further-more to pharmaceutical compositions which comprise these compounds, and to the use of the compounds for the treatment of kinase-induced diseases.
The invention relates to the compounds of the formula I as inhibitors of Raf kinases.
Protein phosphorylation is a fundamental process for the regulation of cellular functions. The coordinated action of both protein kinases and phosphatases controls the degrees of phosphorylation and, hence, the activity of specific target proteins. One of the predominant roles of protein phosphorylation is in signal transduction, where extracellular signals are amplified and propagated by a cascade of protein phosphorylation and dephosphorylation events, for example in the p21ras/Raf pathway.
The p21ras gene was discovered as an oncogene of the Harvey (H-Ras) and Kirsten (K-Ras) rat sarcoma viruses. In humans, characteristic mutations in the cellular Ras gene (c-Ras) have been associated with many different types of cancer. These mutant alleles, which render Ras constitutively active, have been shown to transform cells, such as, for example, the murine cell line NIH 3T3, in culture.
The p21ras oncogene is a major contributor to the development and progression of human solid carcinomas and is mutated in 30% of all human carcinomas (Bolton et al. (1994) Ann. Rep. Med. Chem., 29, 165-74; Bos. (1989) Cancer Res., 49, 4682-9). In its normal, unmutated form, the Ras protein is a key element of the signal transduction cascade directed by growth factor receptors in almost all tissues (Avruch et al. (1994) Trends Biochem. Sci., 19, 279-83).
Biochemically, Ras is a guanine nucleotide binding protein, and cycling between a GTP-bound activated and a GDP-bound resting form is strictly controlled by Ras endogenous GTPase activity and other regulatory proteins. The Ras gene product binds to guanine triphosphate (GTP) and guanine diphosphate (GDP) and hydrolyses GTP to GDP. Ras is active in the GTP-bound state. In the Ras mutants in cancer cells, the endogenous GTPase activity is reduced and the protein consequently transmits constitutive growth signals to downstream effectors, such as, for example, the enzyme Raf kinase. This leads to the cancerous growth of the cells which carry these mutants (Magnuson et al. (1994) Semin. Cancer Biol., 5, 247-53). The Ras proto-oncogene requires a functionally intact C-Raf-1 proto-oncogene in order to transduce growth and differentiation signals initiated by receptor- and non-receptor-type tyrosine kinases in higher eukaryotes.
Activated Ras is necessary for the activation of the C-Raf-1 proto-onco-gene, but the biochemical steps through which Ras activates the Raf-1 protein (Ser/Thr) kinase are now well characterised. It has been shown that inhibiting the effect of active Ras by inhibiting the Raf kinase signalling pathway by administration of deactivating antibodies to Raf kinase or by co-expression of dominant negative Raf kinase or dominant negative MEK (MAPKK), the substrate of Raf kinase, leads to reversion of transformed cells to the normal growth phenotype, see: Daum et al. (1994) Trends Biochem. Sci., 19, 474-80; Fridman et al. (1994) J. Biol. Chem., 269, 30105-8. Kolch et al. (1991) Nature, 349, 426-28) and for a review Weinstein-Oppenheimer et al. Pharm. & Therap. (2000), 88, 229-279.
Similarly, inhibition of Raf kinase (by antisense oligodeoxynucleotides) has been correlated in vitro and in vivo with inhibition of the growth of a variety of human tumour types (Monia et al., Nat. Med. 1996, 2, 668-75); Geiger et al. (1997), Clin. Cancer Res. 3(7):1179-85; Lau et al. (2002), Antisense Nucl. Acid. Drug Dev. 12(1): 11-20; Mc Phillips et al. (2001), Br. J. Cancer 85(11): 1754-8).
Raf serine- and threonine-specific protein kinases are cytosolic enzymes that stimulate cell growth in a variety of cellular systems (Rapp, U. R., et al. (1988) in The Oncogene Handbook; T. Curran, E. P. Reddy and A. Skalka (eds.) Elsevier Science Publishers; The Netherlands, pp. 213-253; Rapp, U. R., et al. (1988) Cold Spring Harbor Sym. Quant. Biol. 53:173-184; Rapp, U. R., et al. (1990) Inv Curr. Top. Microbiol. Immunol. Potter and Melchers (eds.), Berlin, Springer-Verlag 166:129-139).
Three isozymes have been characterised:
C-Raf (Raf-1) (Bonner, T. I., et al. (1986) Nucleic Acids Res. 14:1009-1015). A-Raf (Beck, T. W., et al. (1987) Nucleic Acids Res. 15:595-609), and B-Raf (Qkawa, S., et al. (1998) Mol. Cell. Biol. 8:2651-2654; Sithanandam, G. et al. (1990) Oncogene:1775). These enzymes differ in their expression in various tissues. Raf-1 is expressed in all organs and in all cell lines that have been examined, and A- and B-Raf are expressed in urogenital and brain tissues respectively (Storm, S. M. (1990) Oncogene 5:345-351).
Raf genes are proto-oncogenes: they can initiate malignant transformation of cells when expressed in specifically altered forms. Genetic changes that lead to oncogenic activation generate a constitutively active protein kinase by removal of or interference with an N-terminal negative regulatory domain of the protein (Heidecker, G., et al. (1990) Mol. Cell. Biol. 10:2503-2512; Rapp, U. R., et al. (1987) in Oncogenes and Cancer; S. A. Aaronson, J. Bishop, T. Sugimura, M. Terada, K. Toyoshima and P. K. Vogt (eds.) Japan Scientific Press, Tokyo). Microinjection into NIH 3T3 cells of oncogenically activated, but not wild-type, versions of the Raf protein prepared with Escherichia coli expression vectors results in morphological transformation and stimulates DNA synthesis (Rapp, U. R., et al. (1987) in Oncogenes and Cancer; S. A. Aaronson, J. Bishop, T. Sugimura, M. Terada, K. Toyoshima, and P. K. Vogt (eds.) Japan Scientific Press, Tokyo; Smith, M. R., et al. (1990) Mol. Cell. Biol. 10:3828-3833).
Activating mutants of B-Raf have been identified in various types of human cancer, for example of the intestine, the ovaries, melanomas and sarco-mas (Davies, H. et al. (2002), Nature 417, 949-945; published online 9 Jun. 2002, 10.1038/nature00766). The predominant mutation is a single phosphomimetic substitution in the kinase activation domain (V599E), which results in constitutive kinase activity and transformation of NIH3T3 cells.
The process of angiogenesis is the development of new blood vessels, generally capillaries, from pre-existing vasculature. Angiogenesis is defined as involving (i) activation of endothelial cells; (ii) increased vascular permeability; (iii) subsequent dissolution of the basement membrane and extravisation of plasma components leading to formation of a provisional fibrin gel extracellular matrix; (iv) proliferation and mobilisation of endothelial cells; (v) reorganisation of mobilised endothelial cells to form functional capillaries; (vi) capillary loop formation; and (vii) deposition of basement membrane and recruitment of perivascular cells to newly formed vessels.
Normal angiogenesis is activated during tissue growth, from embryonic development through maturity, and then enters a period of relative quiescence during adulthood.
Normal angiogensesis is also activated during wound healing and at certain stages of the female reproductive cycle. Inappropriate or pathological angiogenesis has been associated with several conditions, including various retinopathies; ischemic disease; atherosclerosis; chronic inflammatory disorders; rheumatoid arthritis, and cancer. The role of angiogenesis in conditions is discussed, for instance, in Fan et al, Trends in Pharmacol Sci. 16:54 66; Shawver et al, DOT Vol. 2, No. 2 Feb. 1997; Folkmann, 1995, Nature Medicine 1:27-31.
In cancer, the growth of solid tumors has been shown to be angiogenesis-dependent. (see Folkmann, J., J. Nat'l. Cancer Inst., 1990, 82, 4-6.) Consequently, the targeting of pro-angiogenic pathways is a strategy being widely pursued in order to provide new therapeutics in these areas of great, unmet medical need.
Raf is involved in angiogenic processes. Endothelial growth factors (for example vascular endothelial growth factor VEGF or basic fibroblast growth factor bFGF) activate receptor tyrosine kinases (for example VEGFR-2) and signal through the Ras/Raf/Mek/Erk kinase cascade and protect endothelial cells against apoptosis (Alavi et al. (2003), Science 301, 94-96; Hood, J. D. et al. (2002), Science 296, 2404; Mikula, M. et al. (2001), EMBO J. 20, 1952; Hauser, M. et al. (2001), EMBO J. 20, 1940; Wojnowski et al. (1997), Nature Genet. 16, 293). Activation of VEGFR-2 by VEGF is a critical step in the signal transduction pathway that initiates tumor angiogenesis. VEGF expression may be constitutive to tumour cells and can also be upregulated in response to certain stimuli. One such stimulus is hypoxia, where VEGF expression is upregulated in both tumour and associated host tissues. The VEGF ligand activates VEGFR-2 by binding to its extracellular VEGF binding site. This leads to receptor dimerisation of VEGFRs and autophosphorylation of tyrosine residues at the intracellular kinase domain of VEGFR-2. The kinase domain causes a transfer of a phosphate from ATP to the tyrosine residues, thus providing binding sites for signalling proteins downstream of VEGFR-2, ultimately leading to initiation of angiogenesis (McMahon, G., The Oncologist, Vol. 5, No. 90001, 3-10, April 2000).
Mice with a targeted disruption in the B-Raf gene die of vascular defects during development (Wojnowski, L. et al. 1997, Nature Genetics 16, page 293-296). These mice show defects in the formation of the vascular sys-tem and in angiogenesis, for example enlarged blood vessels and increased apoptotic death of differentiated endothelial cells.
Consequently, activated Raf-1 is an intracellular activator of cell growth. Raf-1 protein serine kinase is a candidate for the downstream effector of mitogen signal transduction, since Raf oncogenes overcome growth arrest resulting from a block of cellular Ras activity due either to a cellular mutation (Ras revertant cells) or microinjection of anti-Ras antibodies (Rapp, U. R., et al. (1988) in The Oncogene Handbook, T. Curran, E. P. Reddy and A. Skalka (eds.), Elsevier Science Publishers; The Netherlands, pp. 213-253; Smith, M. R., et al. (1986) Nature (London) 320:540-543).
C-Raf function is required for transformation by a variety of membrane-bound oncogenes and for growth stimulation by mitogens contained in serums (Smith, M. R., et al. (1986) Nature (London) 320:540-543). Raf-1 protein serine kinase activity is regulated by mitogens via phosphorylation (Morrison, D. K., et al. (1989) Cell 58:648-657), which also effects sub-cellular distribution (Olah, Z., et al. (1991) Exp. Brain Res. 84:403; Rapp, U. R., et al. (1988) Cold Spring Harbor Sym. Quant. Biol. 53:173-184. Raf-1 activating growth factors include platelet-derived growth factor (PDGF) (Morrison, D. K., et al. (1988) Proc. Natl. Acad. Sci. USA 85:8855-8859), colony-stimulating factor (Baccarini, M., et al. (1990) EMBO J. 9:3649-3657), insulin (Blackshear, P. J., et al. (1990) J. Biol. Chem. 265:12115-12118), epidermal growth factor (EGF) (Morrison, R. K., et al. (1988) Proc. Natl. Acad. Sci. USA 85:8855-8859), interleukin-2 (Turner, B. C., et al. (1991) Proc. Natl. Acad. Sci. USA 88:1227) and interleukin-3 and granulocyte macrophage colony-stimulating factor (Carroll, M. P., et al. (1990) J. Biol. Chem. 265:19812-19817).
After mitogen treatment of cells, the transiently activated Raf-1 protein serine kinase translocates to the perinuclear area and the nucleus (Olah, Z., et al. (1991) Exp. Brain Res. 84:403; Rapp, U. R., et al. (1988) Cold Spring Harbor Sym. Quant. Biol. 53:173-184). Cells containing activated Raf are altered in their pattern of gene expression (Heidecker, G., et al. (1989) in Genes and signal transduction in multistage carcinogenesis, N. Colburn (ed.), Marcel Dekker, Inc., New York, pp. 339-374) and Raf onco-genes activate transcription from Ap-I/PEA3-dependent promoters in transient transfection assays (Jamal, S., et al. (1990) Science 344:463-466; Kaibuchi, K., et al. (1989) J. Biol. Chem. 264:20855-20858; Wasylyk, C., et al. (1989) Mol. Cell. Biol. 9:2247-2250).
There are at least two independent pathways for Raf-1 activation by extracellular mitogens: one involving protein kinase C (KC) and a second initiated by protein tyrosine kinases (Blackshear, P. J., et al. (1990) J. Biol. Chem. 265:12131-12134; Kovacina, K. S., et al. (1990) J. Biol. Chem. 265:12115-12118; Morrison, D. K., et al. (1988) Proc. Natl. Acad. Sci. USA 85:8855-8859; Siegel, J. N., et al. (1990) J. Biol. Chem. 265:18472-18480; Turner, B. C., et al. (1991) Proc. Natl. Acad. Sci. USA 88:1227). In each case, activation involves Raf-1 protein phosphorylation. Raf-1 phosphorylation may be a consequence of a kinase cascade amplified by autophosphorylation or may be caused entirely by autophosphorylation initiated by binding of a putative activating ligand to the Raf-1 regulatory domain, analogous to PKC activation by diacylglycerol (Nishizuka, Y. (1986) Science 233:305-312).
One of the principal mechanisms by which cellular regulation is effected is through the transduction of extracellular signals across the membrane that in turn modulate biochemical pathways within the cell. Protein phosphorylation represents one course by which intracellular signals are propagated from molecule to molecule resulting finally in a cellular response. These signal transduction cascades are highly regulated and often overlap, as is evident from the existence of many protein kinases as well as phosphatases. Phosphorylation of proteins occurs predominantly at serine, threonine or tyrosine residues, and protein kinases have therefore been classified by their specificity of phosphorylation site, i.e. serine/threonine kinases and tyrosine kinases. Since phosphorylation is such a ubiquitous process within cells and since cellular phenotypes are largely influenced by the activity of these pathways, it is currently believed that a number of conditions and/or diseases are attributable to either aberrant activation or functional mutations in the molecular components of kinase cascades. Consequently, considerable attention has been devoted to the characterisation of these proteins and compounds that are able to modulate their activity (review article see: Weinstein-Oppenheimer et al. Pharma. &. Therap., 2000, 88, 229-279).
The synthesis of small compounds which specifically inhibit, regulate and/or modulate signal transduction by Raf kinases is therefore desirable and an aim of the present invention.
It has been found that the compounds according to the invention and salts thereof have very valuable pharmacological properties while being well tolerated.
In particular, they exhibit tyrosine kinase inhibiting properties.
It has furthermore been found that the compounds according to the invention are inhibitors of the enzyme Raf kinase. Since the enzyme is a down-stream effector of p21ras, the inhibitors prove to be suitable in pharmaceutical compositions for use in human or veterinary medicine where inhibition of the Raf kinase pathway is indicated, for example in the treatment of tumours and/or cancerous cell growth mediated by Raf kinase. In particular, the compounds are suitable for the treatment of human and animal solid cancers, for example murine cancer, since the progression of these cancers is dependent upon the Ras protein signal transduction cascade and therefore susceptible to treatment by interruption of the cascade, i.e. by inhibiting Raf kinase. Accordingly, the compound according to the invention or a pharmaceutically acceptable salt thereof is administered for the treatment of diseases mediated by the Raf kinase pathway, especially cancer, including solid cancers, such as, for example, carcinomas (for example of the lungs, pancreas, thyroid, bladder or colon), myeloid diseases (for example myeloid leukaemia) or adenomas (for example villous colon adenoma), pathological angiogenesis and metastatic cell migration. The compounds are furthermore suitable for the treatment of complement activation dependent chronic inflammation (Niculescu et al. (2002) Immunol. Res., 24:191-199) and HIV-1 (human immunodeficiency virus type 1) induced immunodeficiency (Popik et al. (1998) J Virol, 72: 6406-6413), infection disease, influenza A virus (Pleschka, S. et al. (2001), Nat. Cell. Biol., 3(3):301-5) and Heliobacter pylori infection (Wessler, S. et al. (2002), FASEB J., 16(3): 417-9).
Surprisingly, it has been found that compounds according to the invention are able to interact with signalling pathways, especially the signalling pathways described herein and preferably the Raf kinase signalling pathway. The compounds according to the invention preferably exhibit an advantageous biological activity which can easily be demonstrated in enzyme-based assays, for example assays as described herein. In such enzyme-based assays, the compounds according to the invention preferably exhibit and cause an inhibiting effect, which is usually documented by IC50 values in a suitable range, preferably in the micromolar range and more preferably in the nanomolar range.
As discussed herein, these signalling pathways are relevant for various diseases. Accordingly, the compounds according to the invention are suit-able for the prophylaxis and/or treatment of diseases that are dependent on the said signalling pathways by interacting with one or more of the said signalling pathways.
The present invention therefore relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of the signalling pathways described herein. The invention therefore preferably relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of the Raf kinase pathway. The invention therefore preferably relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of Raf kinase. The invention still more preferably relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of one or more Raf kinases selected from the group consisting of A-Raf, B-Raf and C-Raf-1. The invention particularly preferably relates to compounds according to the invention as promoters or inhibitors, preferably as inhibitors, of C-Raf-1.
The present invention furthermore relates to the use of one or more compounds according to the invention in the treatment and/or prophylaxis of diseases, preferably the diseases described herein, that are caused, mediated and/or propagated by Raf kinases and in particular diseases that are caused, mediated and/or propagated by Raf kinases selected from the group consisting of A-Raf, B-Raf and C-Raf-1. The diseases discussed here are usually divided into two groups, hyperproliferative and non-hyperproliferative diseases. In this connection, psoriasis, arthritis, inflammation, endometriosis, scarring, benign prostatic hyperplasia, immunological diseases, autoimmune diseases and immunodeficiency diseases are regarded as non-cancerous diseases, of which arthritis, inflammation, immunological diseases, autoimmune diseases and immunodeficiency diseases are usually regarded as non-hyperproliferative diseases. In this connection, brain cancer, lung cancer, squamous cell cancer, bladder cancer, gastric cancer, pancreatic cancer, hepatic cancer, renal cancer, colorectal cancer, breast cancer, head cancer, neck cancer, oesophageal cancer, gynaecological cancer, thyroid cancer, lymphomas, chronic leukaemia and acute leukaemia are to be regarded as cancerous diseases, all of which are usually regarded as hyperproliferative diseases. Especially cancerous cell growth and especially cancerous cell growth mediated by Raf kinase is a disease which is a target of the present invention. The pre-sent invention therefore relates to compounds according to the invention as medicaments and/or medicament active ingredients in the treatment and/or prophylaxis of the said diseases and to the use of compounds according to the invention for the preparation of a pharmaceutical for the treatment and/or prophylaxis of the said diseases as well as to a method for the treatment of the said diseases which comprises the administration of one or more compounds according to the invention to a patient in need of such an administration.
It can be shown that the compounds according to the invention have an antiproliferative action in vivo in a xenotransplant tumour model. The compounds according to the invention are administered to a patient having a hyperproliferative disease, for example to inhibit tumour growth, to reduce inflammation associated with a lymphoproliferative disease, to inhibit trans-plant rejection or neurological damage due to tissue repair, etc. The present compounds are suitable for prophylactic or therapeutic purposes. As used herein, the term “treatment” is used to refer to both prevention of diseases and treatment of pre-existing conditions. The prevention of proliferation is achieved by administration of the compounds according to the invention prior to the development of overt disease, for example to prevent the growth of tumours, prevent metastatic growth, diminish restenosis associated with cardiovascular surgery, etc. Alternatively, the compounds are used for the treatment of ongoing diseases by stabilising or improving the clinical symptoms of the patient.
The host or patient can belong to any mammalian species, for example a primate species, particularly humans; rodents, including mice, rats and hamsters; rabbits; horses, cows, dogs, cats, etc. Animal models are of interest for experimental investigations, providing a model for treatment of human disease.
The susceptibility of a particular cell to treatment with the compounds according to the invention can be determined by in vitro tests. Typically, a culture of the cell is combined with a compound according to the invention at various concentrations for a period of time which is sufficient to allow the active agents to induce cell death or to inhibit migration, usually between about one hour and one week. In vitro testing can be carried out using cultivated cells from a biopsy sample. The viable cells remaining after the treatment are then counted.
The dose varies depending on the specific compound used, the specific disease, the patient status, etc. A therapeutic dose is typically sufficient considerably to reduce the undesired cell population in the target tissue while the viability of the patient is maintained. The treatment is generally continued until a considerable reduction has occurred, for example an at least about 50% reduction in the cell burden, and may be continued until essentially no more undesired cells are detected in the body.
For the identification of a signal transduction pathway and for detection of interactions between various signal transduction pathways, various scientists have developed suitable models or model systems, for example cell culture models (for example Khwaja et al., EMBO, 1997, 16, 2783-93) and models of transgenic animals (for example White et al., Oncogene, 2001; 20, 7064-7072). For the determination of certain stages in the signal transduction cascade, interacting compounds can be utilised in order to modulate the signal (for example Stephens et al., Biochemical J., 2000, 351, 95-105). The compounds according to the invention can also be used as reagents for testing kinase-dependent signal transduction pathways in animals and/or cell culture models or in the clinical diseases mentioned in this application.
Measurement of the kinase activity is a technique which is well known to the person skilled in the art. Generic test systems for the determination of the kinase activity using substrates, for example histone (for example Alessi et al., FEBS Lett. 1996, 399, 3, pages 333-338) or the basic myelin protein are described in the literature (for example Campos-González, R. and Glenney, Jr., J. R. 1992, J. Biol. Chem. 267, page 14535).
For the identification of kinase inhibitors, various assay systems are available, for example Walters et al., Nature Drug Discovery 2003, 2; 259-266). In scintillation proximity assay (Sorg et al., J. of. Biomolecular Screening, 2002, 7, 11-19) and flashplate assay, the radioactive phosphorylation of a protein or peptide as substrate with γATP is measured. In the presence of an inhibitory compound, a decreased radioactive signal, or none at all, is detectable. Furthermore, homogeneous time-resolved fluorescence resonance energy transfer (HTR-FRET) and fluorescence polarisation (FP) technologies are suitable as assay methods (Sills et al., J. of Biomolecular Screening, 2002, 191-214).
Other non-radioactive ELISA assay methods use specific phospho-antibodies (phospho-ABs). The phospho-AB binds only the phosphorylated substrate. This binding can be detected by chemiluminescence using a second peroxidase-conjugated anti-sheep antibody (Ross et al., 2002, Biochem. J., 2002, 366.977-981).
There are many diseases associated with deregulation of cell proliferation and cell death (apoptosis). The conditions of interest include, but are not limited to, the following. The compounds according to the invention are suitable for the treatment of a variety of conditions where there is proliferation and/or migration of smooth muscle cells and/or inflammatory cells into the intimal layer of a vessel, resulting in restricted blood flow through that vessel, for example in the case of neointimal occlusive lesions. Occlusive graft vascular diseases of interest include atherosclerosis, graft coronary vascular disease after transplantation, vein graft stenosis, peri-anastomotic prosthetic restenosis, restenosis after angioplasty or stent placement, and the like.